linux-kernel - Re: [PATCH v2 1/3] firmware: arm_scpi: add support for device power state management

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Date:	Thu, 16 Jun 2016 19:03:52 +0100
From:	"Jon Medhurst (Tixy)" <tixy@...aro.org>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Suzuki K Poulose <suzuki.poulose@....com>
Subject: Re: [PATCH v2 1/3] firmware: arm_scpi: add support for device power
 state management

On Thu, 2016-06-16 at 11:37 +0100, Sudeep Holla wrote:
> SCPI protocol supports device power state management. This deals with
> power states of various peripheral devices in the system other than the
> core compute subsystem.
> 
> This patch adds support for the power state management of those
> peripheral devices.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>

Reviewed-by: Jon Medhurst <tixy@...aro.org>
Tested-by: Jon Medhurst <tixy@...aro.org>

I've also tested this series on Juno r2 together with the coresight
changes [1], to the extent that enabling various kernel configs gets the
kernel log showing several lines like:

coresight-etm4x 22040000.etm: ETM 4.0 initialized

and if I omit the power domain entries from device-tree then boot hangs
as you indicated it would be expected due to coresight hardware being
powered off.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/433769.html


> ---
>  drivers/firmware/arm_scpi.c   | 30 ++++++++++++++++++++++++++++++
>  include/linux/scpi_protocol.h |  2 ++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
> index 51c6db0774cc..438893762076 100644
> --- a/drivers/firmware/arm_scpi.c
> +++ b/drivers/firmware/arm_scpi.c
> @@ -231,6 +231,11 @@ struct sensor_value {
>  	__le32 hi_val;
>  } __packed;
> 
> +struct dev_pstate_set {
> +	u16 dev_id;
> +	u8 pstate;
> +} __packed;
> +
>  static struct scpi_drvinfo *scpi_info;
> 
>  static int scpi_linux_errmap[SCPI_ERR_MAX] = {
> @@ -537,6 +542,29 @@ static int scpi_sensor_get_value(u16 sensor, u64 *val)
>  	return ret;
>  }
> 
> +static int scpi_device_get_power_state(u16 dev_id)
> +{
> +	int ret;
> +	u8 pstate;
> +	__le16 id = cpu_to_le16(dev_id);
> +
> +	ret = scpi_send_message(SCPI_CMD_GET_DEVICE_PWR_STATE, &id,
> +				sizeof(id), &pstate, sizeof(pstate));
> +	return ret ? ret : pstate;
> +}
> +
> +static int scpi_device_set_power_state(u16 dev_id, u8 pstate)
> +{
> +	int stat;
> +	struct dev_pstate_set dev_set = {
> +		.dev_id = cpu_to_le16(dev_id),
> +		.pstate = pstate,
> +	};
> +
> +	return scpi_send_message(SCPI_CMD_SET_DEVICE_PWR_STATE, &dev_set,
> +				 sizeof(dev_set), &stat, sizeof(stat));
> +}
> +
>  static struct scpi_ops scpi_ops = {
>  	.get_version = scpi_get_version,
>  	.clk_get_range = scpi_clk_get_range,
> @@ -548,6 +576,8 @@ static struct scpi_ops scpi_ops = {
>  	.sensor_get_capability = scpi_sensor_get_capability,
>  	.sensor_get_info = scpi_sensor_get_info,
>  	.sensor_get_value = scpi_sensor_get_value,
> +	.device_get_power_state = scpi_device_get_power_state,
> +	.device_set_power_state = scpi_device_set_power_state,
>  };
> 
>  struct scpi_ops *get_scpi_ops(void)
> diff --git a/include/linux/scpi_protocol.h b/include/linux/scpi_protocol.h
> index 35de50a65665..dc5f989be226 100644
> --- a/include/linux/scpi_protocol.h
> +++ b/include/linux/scpi_protocol.h
> @@ -70,6 +70,8 @@ struct scpi_ops {
>  	int (*sensor_get_capability)(u16 *sensors);
>  	int (*sensor_get_info)(u16 sensor_id, struct scpi_sensor_info *);
>  	int (*sensor_get_value)(u16, u64 *);
> +	int (*device_get_power_state)(u16);
> +	int (*device_set_power_state)(u16, u8);
>  };
> 
>  #if IS_REACHABLE(CONFIG_ARM_SCPI_PROTOCOL)
> --
> 2.7.4
>